The present invention relates to integrated circuits, and more specifically, to a recessed metal liner contact with copper fill.
A metal-oxide-semiconductor field-effect transistor (MOSFET) is a transistor used for switching electronic signals. Generally, the MOSFET includes a source, a drain, and a metal oxide gate electrode. The metal gate is electrically insulated from the main semiconductor n-channel or p-channel by a thin layer of insulating material such as, for example, silicon dioxide or a high dielectric constant (high-k) dielectric, which makes the input resistance of the MOSFET relatively high. The gate voltage controls whether the path from drain to source is an open circuit (“off”) or a resistive path (“on”).
N-type field effect transistors (NFET) and p-type field effect transistors (PFET) are two types of complementary MOSFETs. The NFET uses electrons as the current carriers and with n-doped source and drain junctions. The PFET uses holes as the current carriers and with p-doped source and drain junctions. Complementary metal-oxide semiconductor (CMOS) general refers to complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. A FinFET is a type of MOSFET. The FinFET is a double-gate or multiple-gate MOSFET device that mitigates the effects of short channels and reduces drain-induced barrier lowering. The “fin” refers to the narrow channel between source and drain regions. A thin dielectric layer on either side of the fin separates the fin channel from the gate.
In integrated circuits (ICs) such as those using complemental metal-oxide semiconductor (CMOS) technology, for example, pitch scaling is done to reduce device dimensions. Traditionally, source and drain contacts result from a contact metal (e.g., tungsten (W)) being used to fill in a trench formed above the source and drain regions. The fill metal is separated from the spacer that is used to form the trench by a liner. In current ICs, these liners have not been scaled along with the contacts. As a result, the volume of contact metal has been reduced according to the reduced contact size.